This specification relates to information retrieval and image classification.
The Internet provides access to a wide variety of resources, such as image files, audio files, video files, and web pages. A search system can identify resources in response to queries. The queries can be text queries that include one or more search terms or phrases, image queries that include images, or a combination of text and image queries. The search system ranks the resources and provides search results that link to the identified resources. The search results are typically ordered for viewing according to the rank.
With respect to image searches, the relevance of an image to a search query is typically determined based on text associated with the image and/or features of the image itself. For example, relevance of an image appearing on a web page to a search query may be based on text that appears on the web page and within a specified proximity of the image. Likewise, features of an image can be extracted and compared to features of other images, or input as a feature vector into a machine learned system, to identify other images that may be relevant to the image.